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This study aims at validating the accuracy of the new indirect calorimeter (Q-NRG, COSMED, Italy), developed for the ICALIC multicenter study. The validation of accuracy will only be conducted in Geneva center.
The measurements made with the new calorimeter will be compared to the measurements by the mixing chamber method using a mass spectrometer (MAX300-LG, Extrel, USA) for gas composition analysis.
Indirect calorimetry is a method to measure energy expenditure of human subjects by analyzing patient breath gas to measure the amount (volume) of oxygen consumption (VO2) and CO2 production (VCO2). Energy expenditure is calculated by the Weir's equation using the measured VO2 and VCO2 values.
The new calorimeter is equipped with a disposable in-line pneumotach flowmeter, which measures the flow of exhaled gas of patients directly within the mechanical ventilator circuit. It also samples small amount of inhaled and exhaled gas to measure the inhaled and exhaled O2 and CO2 compositions. The new dynamic micro-mixing chamber technique is used to meaure VO2 and VCO2 to derive the energy expenditure.
The mass spectrometer measures the inhaled and exhaled gas compositions. The mass spectrometer samples inhaled gas from the mechanical ventilator circuit. A mixing chamber system is used to collect the expired gas from the outlet of the mechanical ventilator. The collected gas is measured for the second time after diluting with a constant flow of ambient air, which is monitored by an independent mass flow meter. The volume of the expired gas is calculated by comparison of the concentrations of exhaled gas before and after the dilution. The measurements will be used to calculate the VO2 and VCO2 to derive the energy expenditure.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Mechanically ventilated ICU patient | Indirect calorimetry measurements will be conducted using the new calorimeter and the mass spectrometer system at the same time for all enrolled patients. |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Indirect calorimetry | Other | Indirect calorimetry will be conducted using the new calorimeter and mixing chamber method using the mass spectrometer. |
|
| Measure | Description | Time Frame |
|---|---|---|
| Accuracy of Energy expenditure | Energy expenditure calculated as a result of VO2 and VCO2 measurements | immediately after the measurement |
| Measure | Description | Time Frame |
|---|---|---|
| Accuracy of VO2 | Volume of oxygen consumption | immediately after the measurement |
| Accuracy of VCO2 | Volume of CO2 production | immediately after the measurement |
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Inclusion Criteria:
• Mechanically ventilated adult ICU patients
Exclusion Criteria:
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Mechanically ventilated adult ICU patients
| Name | Role | Phone | Extension | |
|---|---|---|---|---|
| Taku Oshima, MD,PhD | Contact | +41 79 5534780 | Oshima.Taku@hcuge.ch | |
| Severine Graf | Contact | Severine.Graf@hcuge.ch |
| Name | Affiliation | Role |
|---|---|---|
| Claude Pichard, MD, PhD | Clinical Nutrition, Geneva University Hospital | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Service of Intensive Care, Geneva University Hospital | Recruiting | Geneva | 1211 | Switzerland |
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| ID | Term |
|---|---|
| D016638 | Critical Illness |
| ID | Term |
|---|---|
| D020969 | Disease Attributes |
| D010335 | Pathologic Processes |
| D013568 | Pathological Conditions, Signs and Symptoms |
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| ID | Term |
|---|---|
| D002153 | Calorimetry, Indirect |
| ID | Term |
|---|---|
| D002151 | Calorimetry |
| D002623 | Chemistry Techniques, Analytical |
| D008919 | Investigative Techniques |
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| Respiratory quotient (RQ) | RQ calculated as a ratio of VCO2 to VO2 | immediately after the measurement |